WASHINGTON, DC, United States (UPI) -- The U.S. Department of
Agriculture was quick to assure the public earlier this week that the
third case of mad cow disease did not pose a risk to them, but what
federal officials have not acknowledged is that this latest case
indicates the deadly disease has been circulating in U.S. herds for at
least a decade.

The second case, which was detected last year in a Texas cow and which
USDA officials were reluctant to verify, was approximately 12 years
old.

These two cases (the latest was detected in an Alabama cow) present a
picture of the disease having been here for 10 years or so, since it
is thought that cows usually contract the disease from contaminated feed they consume as calves. The concern is that humans can contract a
fatal, incurable, brain-wasting illness from consuming beef products
contaminated with the mad cow pathogen.

'The fact the Texas cow showed up fairly clearly implied the existence
of other undetected cases,' Dr. Paul Brown, former medical director of
the National Institutes of Health's Laboratory for Central Nervous
System Studies and an expert on mad cow-like diseases, told United Press International. 'The question was, `How many?` and we still
can't
answer that.'

Brown, who is preparing a scientific paper based on the latest two mad
cow cases to estimate the maximum number of infected cows that
occurred in the United States, said he has 'absolutely no confidence
in USDA tests before one year ago' because of the agency's reluctance
to retest the Texas cow that initially tested positive.